Medical ultrasounds and shock waves penetrating deep within bodies can modulate biological functions, inducing therapeutic effects like angiogenesis and bone growth. This discipline, known as mechanobiology, has recently received heightened attention, particularly around cellular response mechanisms to mechanical stimuli. We aim to uncover the mechanisms and effects of acoustic stimulation, utilizing direct visualizations of acoustic interactions with cells and observing the subsequent cellular responses.

References

• T. Saiki et al., “Single-shot optical imaging with spectrum circuit bridging timescales in high-speed photography.” Science Advances 9, eadj8608 (2023).

• Y. Ito, D. Veysset, S. E. Kooi, D. Martynowych, K. Nakagawa and K. A. Nelson, “Interferometric and fluorescence analysis of shock wave effects on cell membrane.” Communications Physics 3, 124 (2020).

• T. Takahashi, K. Nakagawa, S. Tada and A. Tsukamoto, “Low-energy shock waves evoke intracellular Ca2+ increases independently of sonoporation.” Scientific Reports 9, 3218 (2019).

Light serves as a crucial instrument in neuroscience, utilized for optogenetics, fluorescence imaging of neural networks, brain function measurement, and so on. However, due to the inherent optical scattering and absorption by biological tissues, its reach into deeper regions is constrained. To overcome this limitation, we are pioneering advanced acoustic-optical technologies that enable the delivery and detection of light in deeper regions by modulating light propagation within the brain or biological specimens.

References

• S. Wunderl, A. Ishijima, E. A. Susaki, Z. Xu, H. Song, H. Zha, T. Azuma, I. Sakuma, H. Fukuoka, E. Okada, H. R. Ueda, S. Takagi and K. Nakagawa, “Acoustic light-sheet microscopy.” bioRxiv: doi.org/10.1101/2021.08.20.457051

• A. Ishijima, U. Yagyu, K. Kitamura, A. Tsukamoto, I. Sakuma and K. Nakagawa, “Nonlinear photoacoustic waves for light guiding to deep tissue sites.” Optics Letters 44, 3006-3009 (2019).

We are resolving issues encountered at clinical sites by leveraging optical and acoustic technologies. For instance, we have visualized particle dispersion behaviors amidst recent COVID-19 outbreak situations. Additionally, we are advancing tools for the analysis of ultrasonic diagnostic images and observing high-speed phenomena occurring during surgeries.

References

• H. Kato, T. Ohya, Y. Arai and K. Nakagawa, “Visualization of droplets produced by nebulizer — Addressing the controversial use of nebulizers during the COVID-19 pandemic.” QJM: An International Journal of Medicine 114, 623-624 (2021).

We have developed the world's fastest camera using ultra-short pulses. This technique allows us to capture non-repetitive events with physical-limited temporal resolution. By utilizing this imaging method, we mainly focus on the light-matter interaction, particularly on single-shot imaging of ultrafast phenomena occurring during ultrashort-pulse laser processing. Additionally, we are conducting research on the next-generation high-speed imaging.

References

• K. Shimada et al., “Spectrum shuttle for producing spatially shapable GHz burst pulses.” Advanced Photonics Nexus 3, 016002 (2023).

• T. Saiki et al., “Sequentially timed all-optical mapping photography boosted by a branched 4ƒ system with a slicing mirror.” Optics Express 28, 31914-31922 (2020).

• K. Nakagawa et al., “Sequentially timed all-optical mapping photography (STAMP).” Nature Photonics 8, 695–700 (2014).